Electrically controlled door lock

ABSTRACT

An electrically controlled door lock ( 11 ) provided with a blocking member ( 21 ) and a detent ( 20 ), the blocking member being in contract with an electrically controlled actuator ( 24 ) such as a piezo-electric member which is used to control movement of the blocking member which in turn causes either the release of a locking member ( 12 ) from a door to allow the door to be opened or the engagement of the locking member to prevent the door from being opened.

The present invention relates to door locks and more particularly to adoor lock which is electrically controlled.

It is known to provide door locks which are a combination of aconventional door lock which can be activated by a key but which canalso be released by means of an electrical control signal so that thedoor can be pushed open without the use of a key. These are common inapartment blocks.

Customarily, the electrical control signal is used to move a member outof position to such an extent that the locking member attached to thedoor no longer prevents the door being pushed open.

Despite the fact that such locks have been available for a considerablenumber of years, there still exists the need to provide a reliableelectrically actuated arrangement at low cost and particularly one whichcan be installed in either a normally closed or normally open condition.

The present invention provides an electrically activated door lock inwhich a piezo electric member is used to control movement of a blockingmember which in turn controls the latching of the door.

Preferably, the blocking member and the retaining member are shaped soas to permit movement of the blocking member to either release thelocking member to allow a door to be opened or engage the member so asto prevent the door being opened.

In order that the present invention be more readily understood, anembodiments thereof will now be described by way of example withreference to the accompanying drawings in which:—

FIG. 1 shows a diagrammatic representation of an electrically activatedlatching mechanism according to a first embodiment of the presentinvention;

FIG. 2 shows diagrammatically a reversing mechanism capable of alteringthe operation of the mechanism shown in FIG. 1 from a normally opencondition to a normally closed condition;

FIG. 3 shows a section of the electrically actuated latching mechanismaccording to a second embodiment of the present invention;

FIG. 4 shows the mechanism shown in FIG. 3 initially set in a reversecondition; and

FIG. 5 shows the overall assembly of the latching mechanism according tothe second embodiment of the present invention.

Referring now to FIG. 1, this shows a door 10 provided with a lock 11having a retractable locking member 12 which is normally retracted bymeans of a manually engageable knob 13 or a key in the conventionalmanner. The latching member 12 is received in a recess in a door jamb 14and in the normal condition is arranged to engage with a blocking member15 which prevents the door being opened unless the latching member 12 isretracted.

In order to electrically control the lock, the blocking member 15 ispivotal in the direction of the arrow A if it is desired to permitsomeone without a key opening the door. The pivotal movement issufficient to allow the latching member 12 to clear the member 15 onsimply pushing the door.

Movement of the member 15 in the direction of the arrow A is controlledby a pawl 20 which engages the end of the member 15 but is capable ofbeing moved out of the way of the end of the member 15 so as to permitthe member 15 to rotate in the direction of the arrow A.

Movement of the pawl 20 is in turn electrically controlled by means of aindex member 21. In one position of the index member 21 rotationalmovement of the pawl 20 is inhibited due to engagement with the member21. This in turn inhibits rotational movement of the member 15 in thedirection of the arrow A when the door is pushed. However, if anelectrical signal is supplied to a suitable actuator, the index member21 is moved to a second position where, if the door is pushed, themember 15 attempts to move in the direction of the arrow A. This causesthe pawl 20 to attempt to move arcuately upwards which it can now do dueto the fact that the blocking member has moved to its second position.In this way, the door can simply be pushed open.

Electrical control of the member 21 is achieved by means of apiezo-electric actuator which, when pulsed, will cause the blockingmember to move from the first to the second position. To ensure thatmechanical forces derived from the locking member are not transferred tothe piezo-electric actuator 24, the member 21 is resiliently coupled tothe actuator 24 and in this case this is achieved by means of a spring25.

A particular feature of the preferred embodiment is that the contactsurfaces of the member 21 and the pawl 20 are shaped so that simply bypresetting the orientation of the member 21 and pawl 20 the lock canoperate so that the door can either be in a normally open or a normallyclosed condition and the application of the electrical control signallocks or opens the door as desired. In this embodiment this is achievedby the member 21 being provided with two projecting teeth 30 as shown inFIG. 2 which are spaced apart. The contact surface of the pawl 20 isprovided with mating projections and recesses with the recesses 31 beinglocated at the same pitch as the projections 30 on the blocking member21 and consequently spaced apart by the same amount. By arranging thaton initial installation the members 21 and 20 are arranged so that theprojections 30 on the member 21 are normally arranged to be received inrecesses 31 in the initial unenergised condition of the piezo-electricmember 24, the door will be a normally open door which when the blockingmember is moved in the direction of the arrow X in FIG. 2 results in theprojections 30 meeting the projections 32 on the detent 20 in the eventthat the door is pushed which prevents the detent from rotating andconsequently the door from being opened. It will be appreciated that byinitially setting the reverse conditions the door will be normallyclosed but will be capable of being pushed open when the blocking memberis moved under the control of the piezo-electric actuator so that theprojections 30 mate with the recesses 31.

The manner in which the operation of the lock can be preset in either ofthe embodiments is a matter of design choice but could be achievedsimply by providing the pivot of the pawl 20 in the form of a bar alongwhich the detent 20 is slid. Likewise, the member 21 could be moved ifit were located in a slide way.

FIG. 3 shows a second embodiment of the electrically activated latchingmechanism according to the present invention. The same referencenumerals are used as the first embodiment for the same features.

The mechanism is similar to the first embodiment and includes a strikeplate member 16. The strike plate 16 is positioned such that movement ofthe strike plate causes the movement of the member 15.

In use, a locking member (not shown) in a door pushes against the strikemember 16 which causes a torque movement with rotation about axis B.This torque is transmitted to the member 15 via suitably angled surfacesto provide a first stage of force reduction. The resultant torquecreated on the member 15 is transferred to the pawl 20 which isrotatably connected to the casing which is not shown in FIG. 3. The pawl20 and member 15 move about axis C and axis D respectively with the twoaxis being parallel to each other.

The index member 21, as in the first embodiment, moves radially withrespect to the pawl 20 and is electrically controlled by means of apiezo-electric actuator.

There are protrusions on the member 21, that correspond to protrusionson the pawl 20 such that when the two sets are aligned as in FIG. 3, theindex member 21 is pushed against an immovable surface that forms partof the casing, not shown. The compressive stress prevents rotation ofthe pawl 20 and hence the strike 16 is unable to rotate and themechanism is locked.

Movement of the member 21 causes the protrusions to become misalignedand the pawl 20 is free to rotate and the lock is open.

Additionally, the mechanism in the second embodiment may be initiallyset in reverse conditions to alter the mechanism from a normally lockedcondition to a normally unlocked condition. This may be achieved byinitially misaligning the set of protrusions 30 on the member 21 andprotrusions 32 on pawl 20 as shown in FIG. 4 such that the lock is openwhen without power and locks when power is applied.

FIG. 5 shows the overall assembly of the latching mechanism. An externalcam 17 is moveable to set the latching mechanism to a normally open ornormally closed position by causing movement of the index member 21. Thedefault position of the member 21 may be set by the user of themechanism.

1. A latching mechanism arranged to receive a locking member of a lock,the mechanism comprising a means for blocking movement of the lockingmember in a first direction and permitting movement of the lockingmember in the first direction by movement in a direction transverse tothe first direction and a pawl engagemenable with the blocking means,the pawl being electrically controllable in order to selectively controloperation of the blocking means.
 2. A latching mechanism according toclaim 1, wherein the mechanism further comprises an electrical actuatorwhich is in contact with an index member to electrically control thepawl, the index member and the pawl member each being provided with aplurality of protrusions.
 3. A latching mechanism according to claim 1wherein the actuator is a piezo electric actuator.
 4. A latchingmechanism according to claim 1, wherein movement of the actuator causesalignment between protrusions of the pawl and protrusions of the indexmember, to enable the latching mechanism to be in a locked condition. 5.A latching mechanism according to claim 1, wherein movement of theactuator causes misalignment of the protrusions of the pawl and theprotrusions of the index member, to enable the latching mechanism to bein an unlocked condition.
 6. A latching mechanism according to claim 2,wherein movement of the actuator causes alignment between protrusions ofthe pawl and protrusions of the index member, to enable the latchingmechanism to be in a locked condition.
 7. A latching mechanism accordingto claim 2, wherein movement of the actuator causes misalignment of theprotrusions of the pawl and the protrusions of the index member, toenable the latching mechanism to be in an unlocked condition.